Tag: stem cell transplants

In patients with aggressive non-Hodgkin’s lymphoma, early stem cell transplants do not improve the overall survival in high-risk patients, but are beneficial in those patients who are at the highest risk.

Lymphomas are cancers of the lymphocytes, which are a specific group of white blood cells. A particular type of lymphoma known as Non-Hodgkin’s lymphoma is more common than the other general type of lymphoma — Hodgkin lymphoma. There are several different subtypes of non-Hodgkin’s lymphoma. The most common non-Hodgkin’s lymphoma subtypes include diffuse large B-cell lymphoma and follicular lymphoma.

The usual treatment for aggressive non-Hodgkin’s lymphoma is a combination of four different chemotherapeutic agents designated as “CHOP,” which stands for Cyclophosphamide (alkylating agent that rituximabdamages DNA), Hydroxydaunorubicin (also called doxorubicin or Adriamycin, also a DNA-damaging agent), Oncovin (vincristine, which binds to microtubules and prevents cells from dividing duplicating by binding to the protein tubulin), and Prednisone or prednisolone (corticosteroids). Recently, many oncologists are adding Rituximab to this drug regimen (but only if the lymphoma is of B-cell origin). Rituximab is a monoclonal antibody that binds to the surface of B-lymphocytes (the very cells that have become cancerous) and facilitates their destruction. This new five-drug regimen, R-CHOP, can drive many patients into remission. However, some relapse and go on to receive stem cell transplants.

This present study, which was directed by Patrick Stiff from the Loyola University Medical Center’s Cardinal Bernardin Cancer Center, was designed to determine if an early stem cell transplant before the patient relapsed increase patient survival. This study examined patients from 40 different clinical sites in the United States and Canada.

397 patients who were in defined groups of high risk or intermediate-high risk of relapsing. After initial chemotherapy treatment, those patients who responded to treatment were randomly assigned to receive an autologous stem cell transplant (125 patients) or to a control group (128 patients) who received three additional cycles of the R-CHOP regimen.

After two years, 69 percent of the transplantation patients had no disease progression, compared with 55 percent of the control group. This is a statistically significant difference, but the two-year survival rates in the transplantation group was 74 percent versus 71 percent in the control group, which was not statistically significant. However, patients in the control group who relapsed were later offered stem cell transplants, which is probably why the differences are not statistically significant.

However, mining the data further reveals something even more interesting. While the stem cell transplants did not improve overall survival among the entire group of high-risk and high-intermediate risk patients, the high-risk patients as an isolated subset rather clearly received a remission and survival benefit from the early stem cell transplants. The two-year survival rate was 82 percent in the stem cell transplant group and 64 percent in the control group, which is statistically significant.

Patrick Stiff and his colleagues concluded: “Early transplantation and late transplantation achieve roughly equivalent overall survival in the combined risk groups.” However, “early transplantation appears to be beneficial for the small group of patients presenting with high-risk disease.”

Stiff hopes that this finding will “trigger discussions between such patients and their physicians as to the feasibility of doing early transplants.”

Patients who receives doses of their own stem cells (so-called autologous stem cell transplants), can tolerate very high doses of chemotherapy and/or radiation. This high-dose treatment kills off many cancer cells, but it also destroys the patient’s immune system. Therefore, prior to the treatment, stem cells are removed from the blood or bone marrow of he patient and infused back into the patient. These stem cells then form a new immune set of immune cells that replace the ones destroyed by the chemotherapy.

Previous studies have shown that patients who undergo autologous stem cell transplants have a higher risk of developing secondary cancers that are caused by the chemotherapy or the radiation. However, this new study did not find a statistically significant difference (11 percent in the control group and 12 percent in the stem cell transplant group) in secondary tumor formation between the two groups.

Stiff and his crew are continuing to crunch the numbers and mine the data. “As years go by, there may be additional analysis that may help fine-tune the results so that we will be able to more carefully and concisely define any potential benefit,” said Stiff.

Because bone marrow transplant patients have had their bone marrows wiped out with radiation or rather severe drugs, their immune systems tend to be kaput until the transplanted bone marrow stem cells start making new immune cells to reconstitute the immune system. Consequently, bone marrow transplant patients can contract a whole host of truly diabolical diseases.

One disease that shows up with some frequency in bone marrow transplant patients is cytomegalovirus (CMV) infections. CMV can cause pneumonia, diarrhea, digestive tract ulcers, and other problems. Some antiviral drugs do exist (ganciclovir, or its prodrug valganciclovir, foscarnet, and cidofovir), but they can cause kidney dysfunction or bone marrow suppression. Neither of these are desirable side effects. Clearly new drugs are needed (see Ahmed, A. Infect Disord Drug Targets. 2011 Oct;11(5):475-503).

A new clinical trial by researchers at Dana-Farber Cancer Institute and Brigham and Women’s Hospital has tested a drug called CMX001. When bone marrow transplant patients took it shortly after transplant, they were much less likely to contract CMV infections that those who did not take the drug.

The study’s lead author, Francisco Marty from Dana-Farber and Brigham and Women’s said: “With current agents, between 3 and 5 percent of allogeneic transplant patients develop CMV disease within six months of transplantation, and a small number of them die of it. There is clearly a need for better treatments with fewer adverse effects. This clinical trial examined whether the disease can be prevented, rather than waiting for blood tests to show that treatment is needed.”

By the time we become adults, most of use have been infected by CMV. However in most cases our immune systems hold it in check. In stem cell transplant patients, however, the immune system is replaced with those of a donor after receiving sizable doses of chemotherapy. During this period, long-dormant viruses, such as CMV, can reactivate and cause CMV disease. CMV is a type of herpes virus. Herpes viruses do a very good job of keeping a low profile and hiding in various types of cells. Only by treating with an effective anti-viral drug can CMV disease be thwarted.

In this Phase 2 clinical trial, 230 stem cell transplant recipients at 27 different centers across the United States were randomly assigned to either the oral CMX001 group to the placebo group. All patients took the drugs or placebos after their bone marrow transplant procedure and the drugs or placebos were taken for 9-11 weeks.

Those patients that took 100 milligrams of CMX001 twice a week, 10% had a CMV event in which CMV was detectable in the blood and the symptoms of CMV disease appeared. However, 37% of those patients who took the placebo had a CMV event. The most common side effect was diarrhea, which is no surprise given the fragile state of these patients.

“The results show the effectiveness of CMX001 in preventing CMV infections in this group of patients,” said Marty. “Because CMX001 is known to be active against other herpes viruses and against adenoviruses that sometimes affect transplant patients, it may be useful as a preventative or treatmentagent for those infections as well.”

Transplantation of adult stem cells into the heart after a heart attack has shown remarkable promise as a treatment for heart patients. The implanted stem cells improve heart function, reinforce heart structure, improve blood circulation in the heart, and reduce the size of the heart scar. Such treatments. however, are hampered by the lack of persistence of implanted stem cells. Only a vast minority of the implanted stem cells survive in the inhospitable environment of the infarcted heart, and the massive cell die-off limits the efficacy of stem cell transplants in the heart.

Fortunately, there are ways to allay this problem. Genetically engineering stem cells to express proteins known to enhance cell survival is one way to ensure that implanted cells survive when implanted. However, getting FDA approval for a clinical trial with genetically-engineered cells will prove to be immensely difficult. A more promising approach is to pretreat the cells with various growth factors, growth conditions or drugs to precondition them to survive in the heart. To that end, scientists at the Davis Heart and Lung Research Institute at Ohio State University have used a commonly prescribed heart drug called “carvedilol” to enhance the survive of bone marrow mesenchymal stem cells in the heart.

Faternat Hassan and his colleagues in the laboratory of Mahmood Khan treated mesenchytmal stem cells (MSCs) from rats with carvedilol and a related drug called “atenolol.” These drugs are members of a drug category called “beta-blockers.”

Beta-blockers are given to lower blood pressure, or to protect the heart after a heart attack from undergoing further deterioration. They bind to the receptors for epinephrine and norepinephrine and block them, which slows the heart down and reduces blood pressure. After a heart attack, however, Beth Haebecker at Oregon Health and Science University has shown that the sympathetic nerves to the heart make very large amounts pf norepinephrine and this is responsible for the remodeling and eventual deterioration of the heart. Beta-blockers can prevent this norepinephrine-based deterioration of the heart.

Over ten years ago, Yue et al. (1992) and Feuerstein (1998) showed that carvedilol has the ability to quench the deleterious effects of damaging molecules. Therefore, carvedilol might protect stem cells from dying in the heart after transplantation.

To begin, Khan’s group cultured MSCs with carvedilol and atenolol for one hour and then subjected the cells to chemical stress by treating them with hydrogen peroxide. The carvedilol-treated cells survived the hydrogen peroxide treatment much better than either the atenolol-treated MSCs or the negative controls that were not pretreated with anything.

For their next experiment, they divided into five groups of six animals each. The first group was operated on but were not give heart attacks. The second group was given heart attacks and no further treatments. The third group was given carvedilol (5 mg/kg body weight) after the heart attack. The fourth group, was MSC treatments, and the fifth group received MSC transplantations plus carvedilol at the previously mentioned dosages. The results showed that the MSC + carvedilol group fared substantially better than all the rest (except for the sham operated group). The heart structure and heart physiology were far superior in the MSC + carvedilol group.

Finally, Khan’ group made a remarkable discovery. Carvedilol prevented the heart from undergoing extensive cell death and decreased the formation of scar tissue. When combined with MSCs, carvedilol’s effect on cell death was amplified. Further investigation demonstrated that carvedilol prevented activation of a protein called “caspase-3.”

Caspases are proteins that degrade other proteins, but they are activated when the cell is damaged beyond all reasonable expectations of repair and the only fitting response for the cell is to die. This process of programmed cell death is called “apoptosis.” The induction of apoptosis is, as you might guess, very tightly controlled, and one of the main regulators of the initiation of apoptosis are the caspases. Caspases exist as inactive enzymes in the cell, but they are activated if the cells is exposed to drugs,conditions, or chemicals that induce cell death. There are three caspases that activate the rest of them and they are caspase 3, 8, & 9, and of these, caspases 3 and 9 are the most important.

Carvedilol treatment caused a significant down-regulation of caspase-3 in heart muscle cells after a heart attack. Furthermore, it prevented the expression of caspase-3 in implanted MSCs, thus increasing MSC survival. Additionally, genes that are known to improve cell survival were also activated in heart muscle cells after carvedilol and MSC treatment.

Thus carvedilol did double duty. It helped the ailing heart, but it also helped the heart help itself by preventing the untimely death of transplanted MSCs. This allowed the MSCs to work their healing processes for a much longer time. The final result was that the carvedilol + MSC-implanted rats showed hearts that were in much better shape than the those in the other groups with the exception of the sham-operated group.

This also suggests that carvedilol should be used with transplanted MSCs in the next clinical trial that utilizes transplanted MSCs.

Stem cell scientists in Canada have collaborated with biotechnology industries to successfully reverse diabetes mellitus in mice by means of stem cell treatments. This is certainly a medical breakthrough that might lead to treatments in human patients.

The lead researcher, Timothy Kieffer, who is a professor at the University of British Columbia, and scientist from the New Jersey-based company BetaLogics showed that stem cell transplants can restore insulin production and reverse diabetes mellitus in mice.

Beta cells reside in an organ called the pancreas, which is behind the stomach. The pancreas has an “exocrine” function, which means that it secretes materials such as digestive enzymes and bicarbonate ions into a duct, and an endocrine function, which means that it secretes hormones directly into the bloodstream. The exocrine function of the pancreas is accomplished by clusters of cells known as “acinar cells.” Acinar cells cluster around a tiny branch of the pancreatic duct, and they secrete digestive enzymes and bicarbonate ions into the pancreatic duct, which are released into the upper portion of the small intestine (duodenum). These enzymes degrade fats, proteins, nucleic acids, and carbohydrates in the small intestine, which prepares the complex molecules in food for digestion. The endocrine functions are carried out by islands of cells dispersed throughout the pancreas that are away from the pancreatic duct, but clustered around blood vessels. These “pancreatic islets” as they are called secrete hormones that regulate the metabolism of food-derived molecules in our bodies.

There are five types of cells in pancreatic islets: alpha cells, beta cells, delta cells, epsilon cells and PP cells. Alpha cells secrete a hormone called glucagon, which mobilizes store sugar stores in the body and releases them into the bloodstream, this raising blood sugar levels. Beta cells secrete insulin, which stimulates the uptake and metabolism of bloodstream sugar, thus lowering blood sugar levels. Delta cells secrete somatostatin, which regulates growth hormone release by the anterior pituitary, but also affects the release of many hormones in the digestive system and inhibits the release of glucagon and insulin. The epsilon cells secrete a hormone called ghrelin, which is a potent appetite stimulant. The PP cells secrete PP or pancreatic peptide, which helps the pancreas to self-regulate its secretory activities, both exocrine and endocrine.

Once glucose levels rise in the blood, the beta cells release insulin, and when glucose levels in the blood decrease, insulin secretion decreases. This “feedback loop” is essential for proper regulation of blood glucose levels, and beta cells that are immature do not properly respond to rises in blood glucose levels. In this study, however, the research effort completely recreated the insulin/sugar feedback loop that enables insulin levels to automatically rise or fall according to the blood glucose levels.

Damage to the beta cells results in insufficient insulin production and poor regulation of the blood sugar levels. Damage to the beta cells results in type 1 diabetes mellitus, and without the secretion of sufficient quantities in insulin after a meal, the cells do not receive the signal to take up sugar, and are starved from energy. Meanwhile, extremely high sugar levels in the blood react with molecules in the organs of the body, which causes long-term damage to the nervous system, eyes, kidneys, and peripheral tissues. Consequently, type 1 diabetics are at increased risk for amputations, blindness, heart attack, stroke, nerve damage and kidney failure.

Regular injections of insulin are the most common treatment for type 1 diabetes mellitus, but experimental transplants of healthy pancreatic cells from human donors have shown to be effective. Unfortunately, such a treatment is severely limited by the availability of donors.

In this experiment, human embryonic stem cells were differentiated into beta cells and implanted into the diabetic mice. After the stem cell transplant, the diabetic mice were weaned off insulin. Three to four months later, the mice were able to maintain healthy blood sugar levels even after being fed large quantities of sugar. Transplanted cells removed from the mice after several months had all the markings of normal insulin-producing pancreatic cells.

These experiments, however, have one very large caveat. In the words of Kiefer: “We are very excited by these findings, but additional research is needed before this approach can be tested clinically in humans. The studies were performed in diabetic mice that lacked a properly functioning immune system that would otherwise have rejected the cells. We now need to identify a suitable way of protecting the cells from immune attack so that the transplant can ultimately be performed in the absence of any immunosuppression.”

Type 1 diabetes usually results from the immune system of the diabetic patient attacking their own beta cells. Replacing the beta cells mere gives the immune system something that it already recognizes to attack. Therefore, replacing the beta cells with new beta cells from any other source is potentially problematic.

There is a possibility that the beta cells could be implanted inside a porous encasement that is not accessible to the immune system, but can still secrete insulin into the bloodstream in response to increase blood sugar levels. Such a strategy would circumvent the immune system problems.

A genetic condition called “aniridia” results from mutations in the PAX6 gene. Approximately 1/50,000-1/1000,000 babies have aniridia. Aniridia results in the complete absence of an iris, and aniridia patients are unable to adjust to light differences.

Because mutations in the PAX6 gene are dominant, aniridia patients half a 50% chance of passing the aniridia condition to their children.

Fortunately for aniridia patients, limbal stem cells can now be cultured in the laboratory and used in clinical settings (see Di Iorio E, et al., Ocul Surf. 2010;8(3):146-53). A Scottish woman with aniridia has just received on of the first limbal stem cell transplants from a cadaver. These cadaver limbal stem cells were cultured and then transplanted onto the surface of her eye.

This woman, Sylvia Paton, who is 50 years old and from the Scottish town of Corstorphine (a west suburb of Edinburgh), is the first person in the United Kingdom to experience this ground-breaking treatment in February of 2012. Her procedure will hopefully reduce her vision problems and ready her for another procedure whereby her lens will be replaced.

For this procedure, limbal stem cells from a dead donor were cultured in the laboratory. The cells were attached to a membrane and then transplanted onto the surface of the left eye. The operation took a total of three hours.

Before her operation, Mrs. Paton could previously only see dark and light through her eye, but this treatment should repair her cornea, and prepare her for another surgery one year later to remove her cataract.

Dr Ashish Agrawal, the National Health Service consultant ophthalmologist who performed the operation, said: “It is now 12 weeks since the transplant and I am delighted to report that Sylvia is recovering well. Her cornea is clear and I hope that it will continue to maintain clarity. However, this is the first and the major step in the complex visual rehabilitation process and she will require further surgical treatment to restore vision.”

We wish Mrs. Paton well and hope that her vision continues to improve.

Stem cell treatments for heart attacks can improve heart function after a heart attack. This has been repeated shown in laboratory animals and human trials have also established the efficacy of bone marrow-based heart treatments. Despite these successes, there are some indications that the improvements wrought by bone marrow stem cell transplants into the heart are not stable, and the functional increases caused by it are transient.

To determine is functional improvements in the heart are transient or stable, Jaroslaw Kaspzak and his colleagues at the Medical University of Lodz, Poland have published a study in which they treated 60 heart attack patients and then tracked them for two years. Their study was published in the journal Kardiologia Polska, which, fortunately, is in English, since I do not read Polish.

In this study, 60 heart attack patients were treated with primary angioplasty and randomly assigned to two groups. The first group consisted of 40 patients who were treated with standard care, and bone marrow stem cell transplants. The bone marrow cells were harvested 3-11 days after the heart attack. The bone marrow cells were administered to the heart by means of intracoronary catheters (over the wire balloon catheter) very near to the area of the infarct (the area in the heart damaged by the heart attack). The second group of 20 patients were treated with standard care. All patients were subjected to echocardiography before treatment and 1, 3, 6, 12, and 24 months after treatment. Additionally, the percentages of patients who experienced subsequent heart attacks, admission to the hospital for heart failure, or revascularization, was tabulated two years after the treatment.

Just after the heart attack, the heart function of both groups was essentially the same. The fraction of blood pumped from the heart (ejection fraction) in the treated group was 35% ± 6% and 33% ± 7% in the control group (normal is 55% – 70%). The volume of blood left in the heart after it contracts (end systolic volume) was 95 milliliters ± 39 milliliters in the treated group and 99 milliliters ± 49 milliliters in the control group (normal is 50-60 milliliters). The amount of blood in the heart after it fills (end diastolic volume) was 149 ± 48 milliliters in the treated group and 151 ± 65 milliliters in the control group (normal is 120-130 milliliters). The end diastolic volume (EDV) is a measure of the firmness of the heart walls. A damaged heart is not as firm and its flaccid walls expand greatly and take up more volume, which puts further strain upon the heart. Thus a DECREASE in the EDV is an indication of improvement in the heart. Nevertheless, it is clear that before the treatment regimes were instigated, the average medical conditions of the two groups was essentially the same, at least when it comes to the heart.

The results of each treatment strategy are rather telling. The ejection fraction in the control group increased 3.7% one moth after the heart attack, 4.7% by 6 months, 4.8% at 12 months, and 4.7% at 24 months. This this group saw its greatest increase six months after the heart attack and although this increase was stable, it was modest at best. The bone marrow-treated group, however, saw an average ejection fraction increase of 7.1% after one month, 9.3% at 6 months, 11.0% after one year, and 10% after two years. Thus the bone marrow-treated group not only showed a much faster and more robust increase in injection fraction, but an increase that was sustained two years after the procedure. Also, the treated group saw half the percentage of deaths due to cardiac events (5%) than that observed in the control group (10%). The percentage of hospitalizations for heart failure in the treated group (3%) was 20% of that seen in the control group (15%). The rates of revasculaizations and new heart attacks was essentially the same in both groups.

This study joins other long-term studies that have demonstrated long-term improvements in heart attack patients treated with heart infusions with bone marrow-derived stem cells. The REPAIR-AMI clinical trial, which examined 204 heart attack patients, showed stable, long-term benefits that lasted for at least two years for those patients who had been treated with infusions of bone marrow stem cells. Other studies have not found no significant differences between heart attack patients treated with standard care and those who also received bone marrow infusions. However, there are probable explanations for many of these failures. The ASTAMI study that failed to show significant differences between the two groups not only transplanted a lower number of cells than this present study and the successful REPAIR-AMI study. Secondly, the negative FINCELL study used patients whose average ejection fractions were 59% ± 11%. Clinical studies that have tested bone marrow heart infusions have established that those patients with lower ejection fractions are helped the most by them. This is the case of the negative HEBE study; the patients with the lowest ejection fraction showed the greatest improvements relative to the control group, but these improvements were swamped out by those with higher ejection fractions that were not helped nearly as much. Third, the meta-analysis of Martin-Rendon showed that the best time period to treat heart attack patients was 4-7 days after the heart attack. In the HEBE study, patients received bone marrow infusions 7 days after angioplasty. How soon after the heart attack was the angioplasty performed? This is not reported, probably because it varied from patient to patient. Nevertheless, this places the treatment outside the optimum established by other experiments.

Thus, once again, we see that bone marrow treatments for hearts are safe, and effective, and they convey long-term benefits to patients who receive them. Much work remains, since only some people consistently benefit from these treatments. Why is this the case? Only more work will tell.